"Such "paired exchanges," first performed in the U.S. at Rhode Island Hospital in 2000, have taken off in the last seven years or so as a way to shorten what can otherwise be a long wait for a healthy kidney. Some 97,000 people are now on the waiting list maintained by the United Network for Organ Sharing, a nonprofit that manages the federal organ transplant system; the average wait time is generally about three to five years. That's too long for many people: About 12 die each day as they hope for a kidney to turn up. A swap like this one effectively fast-tracks the process. At Northwestern, the period between joining the exchange program and surgery typically varies from about two to six months depending on the difficulty of matching.

"Today, 20 to 30 percent of living donor kidney transplants here are done through the paired exchange program, mostly in four- to eight-person swaps. Each week, clinicians run a computer program to explore potential matches from among the incompatible pairs in the system. "There are actually multiple potential solutions that we can look through," says John Friedewald, a transplant nephrologist and medical director of the kidney transplant program. Northwestern also participates in the UNOS kidney paired donation program, which includes roughly 250 paired donors and candidates across the country. The National Kidney Registry, another nonprofit organization, facilitates hundreds of exchanges a year nationwide. In 2015, the NKR organized the longest swap to date, a 70-person chain involving teams at 26 hospitals.
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"Condreva "was very hard to find a match for, so this was sort of a needle in the haystack," Friedewald says. But early this summer, when the altruistic donor approached Northwestern and was determined to be an answer for Condreva, that kidney was the first domino that allowed the other matches to be made. U.S. News visited Northwestern Memorial in late June to attend the surgeries – and the celebration days later when the donors and recipients met."